Machine tool with floating head



March 18, 1941. E, A. WALKER MACHINE TOOL WITH FLOATING HEAD Filed Sept. 14, 1939 2 Sheets-Sheet 1 March 18, 1941.

E. A. WALKER 2,235,269- MACHINE TOOL WITH FLOATING HEAD Filed Sept. 14, 1939 2 Sheets-Sheet 2 m g h V t\ 3 In "s & a g Q m Patented Mar. 18, 1941 j v are UNITE STATES m me MACHINE TOOL WITH FLoA'rrNG HEAD Ernest A. Walker, Worcester, Mass, assignor to John Bath & Company, Worcester, Mass, a corporation of Massachusetts I Application $.eptember 14, 1939, Serial No. 294,930

6 Claims. (01. 1089) t "z? This invention relates to machine tools and manner. Any usualprovision may be made for particularly to machine tools used in tapping or relative vertical movement between the tool ;T reaming operations. and the work W.

, In modern practice, reamed or tapped tools The parts thus iarjdescribed are of usual commust be held closely to size and must beof unimercial construction, except for the manner of form diameter throughout their length. Tapered, mounting the head It on the base Hi. Inthe or bell-mouthed holes, as well as over-sized holes, usual construction, these parts It and M are lead to expensive rejections. On the other hand, either integral or are rigidly secured together, it is very difficult to secure a tap or reamer but in my construction special provision is made A absolutely concentric with its driving chuck or to permit the head 14 to' float or move horispindle or absolutely perpendicular to the plate zontally in one or more directions relative to the or table on which the work is supported.- Some base ill.

means permitting relative transverse adjustment As shown in Figs. 3 and 4, I provide an interof the tool and work is therefore indicated as mediate rotary bearing member 2%, interposed desirable. between the base It and the head It, and having 15 1 Floating chucks or tool holders have been suga downwardly extended shank portion 2|. The gested but have not been particularly satisfacmember is rotatably supported on a plurality tory, as a tool does not shift readily relative to of balls 24, positioned between the outwardly its driving spindle when the tool is under load. flanged portion of the member 20 and a wear 20 It is the general object of my inventionto plate or ball race 25 mounted on the base I0. 20 provide a machine tool with a floating head in A shield or skirt 21 may be provided to exclude which a tool spindle is rotatably mounted in any dust or dirt from the bearing. usual manner. A further feature of the inven- .The shank 2! is also provided at its lower tion relates to the provision of means for limi'tend with'a ball race vertically adjustable on g ing transverse movement of the head in at least a reduced threaded end portion 3! of the shank 25 one direction, and to the further provision of 26 and secured in adjusted position by a lock nut means permitting limited free angular move- 32. Balls 33 are interposed between the race 30 ment of the head about a vertical axis. and an upper ball race or wear plate 3t flxed n My invention further relates to arrangements inan inner portion of the base 10.

" and combinations of parts which will be here- By the provision of upper and lower ball bear- 30 inafter described and more particularly pointed ings as shown, the intermediate bearing member out in the appended claims. 20 is mounted on the base H] for free rotation A preferred form of the invention is shown in about the common axis of said bearings, and is the drawings, in whichalso held from vertical lost motion.

Fig. 1 is a partial side elevation of a tapping A lug 35 (Fig. 5) projects laterally from the 35 machine embodying my improvements; member 20 between stop screws 36 threaded in Fig. 2 is a. partial rear elevation, looking in brackets 31 and held in adjusted position by lock the direction of the arrow 2 in Fig. 1; nuts 38. The brackets 31 are clamped to the Fig. 3 is an enlarged partial side elevation, side of the base Ill as indicated in Fig. 4. By partly insection and showing the floating conadjusting the screws 3" the angular movement 40 nections; of the member 20 relative to the base IEI may Fig. 4 is a partial sectional rear elevation, taken be limited as desired. along the line 4-4 in Fig. 3; and On its upper surface, the member 20 is pro- Fig. 5 is a sectional plan view, taken along the vided with a transverse dove-tailed bar 40, line 55 in Fig. 4. engaged on both sides by a plurality of balls M.

Referring to the drawings, I have shown parts Gibs 62 and '13 are mounted in the lower face of a reaming or tapping machine comprising a of the head M, the gib lz being secured in fixed fixed base I0, a bracket to support the work W, position by clamping screws 44, and the gib 43 and a head 14 mounted on the base Ill and probeing adjustable by screws 46 and secured by viding a support for a bearing block [5 in which clamping screws 41. 50 a tool spindle I6 is mounted for rotation by a By suitably adjusting the gib 43, the head M concentric motor M. may be permitted free floating movement forward A tap or other tool T is shown as held in the and rearward relative to the member Zil, while spindle It by a chuck l8, but the tool may be lost motion is efiectively prevented. secured in the spindle in any other convenient Stop screws 5! in' projections 5! at the front 55 and rear of the member 20 limit said forward and rearward floating movement of the head I, said stop screws being secured by check nuts 53.

Endwise displacement of the balls 4| in the race ways provided between the bar 40 and the-gibs 42 and 43 may be prevented by stop pins (Fig.

3) or in any other convenient manner.

With my improved machine tool constructed as above described, it will be evident that the tap or other tool T is free to move in a horizontal plane, either forward or rearward with respect to the base In, or angularly about the axis of the base I0. In each case, there is a free or floating movement which, however, is definitely confined between easily adjustable limits. The tap or tool' fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, and means to movably support said spindle head on said fixed base and to provide limited free transverse movement of said spindle head on said base, said supporting means being substantially in the plane of tool operation on the work.

2. In a machine tool having a fixed base and a fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, means to movably support said spindle head on said fixed base and ;to provide limited free transverse movement of said spindle head on said base, and adjustable means to limit such transverse movement.

3. In a machine tool having a fixed base and a fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, means to movably support said spindle head on said fixed base and to provide limited free transverse movement of said spindle head on said base, adjustable means to limit such transverse movement, additional means providing free angular movement of said spindle head on said base, and separate adjustable means to limit said angular movement.

4. In a machine tool having a fixed base and a fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, means to movably support said spindle head on said fixed base, and

a linearanti-friction bearing between said spindle head and said base whichprovides limited free forward and rearward movement of said spindle head relative to said base.

5. In a machine tool having a'fixed base and a fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, means to movably support said spindle head on said fixed base, and a circular anti-friction bearing between said spindle head and said base which provides limited free angular movement of said spindle head relative to said base.

6. In a machine tool having a fixed base and a fixed work support, in combination, a non-rotating spindle head, a tool spindle mounted in said spindle head for rotation about a substantially vertical axis and having a fixed locus of rotation in said spindle head, a spindle-driving motor concentric with said tool spindle, means to movably support said spindle head on said fixed base, an intermediate bearing member interposed between saidspindle head and said fixed base, means providing limited free, angular movement between said base and said member, and means providing free limited linear movement between said mem her and said spindle head.

ERNEST A. WALKER. 

